- create an MS-DOS filesystem under Linux
is used to create an MS-DOS filesystem under Linux on a device
(usually a disk partition). DEVICE
is the special file corresponding to
the device (e.g. /dev/sdXX). BLOCK-COUNT
is the number of blocks on the
device. If omitted, mkfs.fat
automatically determines the filesystem
- Normally, for any filesystem except very small ones,
mkfs.fat will align all the data structures to cluster size, to
make sure that as long as the partition is properly aligned, so will all
the data structures in the filesystem. This option disables alignment;
this may provide a handful of additional clusters of storage at the
expense of a significant performance degradation on RAIDs, flash media or
large-sector hard disks.
- Use Atari variation of the MS-DOS filesystem. This is
default if mkfs.fat is run on an Atari, then this option turns off
Atari format. There are some differences when using Atari format: If not
directed otherwise by the user, mkfs.fat will always use 2 sectors
per cluster, since GEMDOS doesn't like other values very much. It will
also obey the maximum number of sectors GEMDOS can handle. Larger
filesystems are managed by raising the logical sector size. Under Atari
format, an Atari-compatible serial number for the filesystem is generated,
and a 12 bit FAT is used only for filesystems that have one of the usual
floppy sizes (720k, 1.2M, 1.44M, 2.88M), a 16 bit FAT otherwise. This can
be overridden with the -F option. Some PC-specific boot sector
fields aren't written, and a boot message (option -m) is
- -b SECTOR-OF-BACKUP
- Selects the location of the backup boot sector for FAT32.
Default depends on number of reserved sectors, but usually is sector 6.
The backup must be within the range of reserved sectors.
- Check the device for bad blocks before creating the
- Create the file given as DEVICE on the command line,
and write the to-be-created filesystem to it. This can be used to create
the new filesystem in a file instead of on a real device, and to avoid
using dd in advance to create a file of appropriate size. With this
option, the BLOCK-COUNT must be given, because otherwise the
intended size of the filesystem wouldn't be known. The file created is a
sparse file, which actually only contains the meta-data areas (boot
sector, FATs, and root directory). The data portions won't be stored on
the disk, but the file nevertheless will have the correct size. The
resulting file can be copied later to a floppy disk or other device, or
mounted through a loop device.
- -D DRIVE-NUMBER
- Specify the BIOS drive number to be stored in the FAT boot
sector. This value is usually 0x80 for hard disks and 0x00 for floppy
devices or partitions to be used for floppy emulation.
- -f NUMBER-OF-FATS
- Specify the number of file allocation tables in the
filesystem. The default is 2.
- -F FAT-SIZE
- Specifies the type of file allocation tables used (12, 16
or 32 bit). If nothing is specified, mkfs.fat will automatically
select between 12, 16 and 32 bit, whatever fits better for the filesystem
- -h NUMBER-OF-HIDDEN-SECTORS
- Select the number of hidden sectors in the volume.
Apparently some digital cameras get indigestion if you feed them a CF card
without such hidden sectors, this option allows you to satisfy them.
- -i VOLUME-ID
- Sets the volume ID of the newly created filesystem;
VOLUME-ID is a 32-bit hexadecimal number (for example, 2e24ec82).
The default is a number which depends on the filesystem creation
- It is typical for fixed disk devices to be partitioned so,
by default, you are not permitted to create a filesystem across the entire
device. mkfs.fat will complain and tell you that it refuses to
work. This is different when using MO disks. One doesn't always need
partitions on MO disks. The filesystem can go directly to the whole disk.
Under other OSes this is known as the 'superfloppy' format. This switch
will force mkfs.fat to work properly.
- -l FILENAME
- Read the bad blocks list from FILENAME.
- -m MESSAGE-FILE
- Sets the message the user receives on attempts to boot this
filesystem without having properly installed an operating system. The
message file must not exceed 418 bytes once line feeds have been converted
to carriage return-line feed combinations, and tabs have been expanded. If
the filename is a hyphen (-), the text is taken from standard input.
- -M FAT-MEDIA-TYPE
- Specify the media type to be stored in the FAT boot sector.
This value is usually 0xF8 for hard disks and is 0xF0 or a value from 0xF9
to 0xFF for floppies or partitions to be used for floppy emulation.
- -n VOLUME-NAME
- Sets the volume name (label) of the filesystem. The volume
name can be up to 11 characters long. The default is no label.
- -r ROOT-DIR-ENTRIES
- Select the number of entries available in the root
directory. The default is 112 or 224 for floppies and 512 for hard
- -R NUMBER-OF-RESERVED-SECTORS
- Select the number of reserved sectors. With FAT32 format at
least 2 reserved sectors are needed, the default is 32. Otherwise the
default is 1 (only the boot sector).
- -s SECTORS-PER-CLUSTER
- Specify the number of disk sectors per cluster. Must be a
power of 2, i.e. 1, 2, 4, 8, ... 128.
- -S LOGICAL-SECTOR-SIZE
- Specify the number of bytes per logical sector. Must be a
power of 2 and greater than or equal to 512, i.e. 512, 1024, 2048, 4096,
8192, 16384, or 32768. Values larger than 4096 are not conforming to the
FAT file system specification and may not work everywhere.
- Verbose execution.
- Use constants for normally randomly generated or time based
data such as volume ID and creation time. Multiple runs of mkfs.fat
on the same device create identical results with this option. Its main
purpose is testing mkfs.fat.
- Display option summary and exit.
can not create boot-able filesystems. This isn't as easy as you
might think at first glance for various reasons and has been discussed a lot
simply will not support it ;)
The home for the dosfstools
project is its
were written by
and others. The current maintainer is